User:Aaparikh/Stony coral (Pavona gigantea)

Description
Pavona gigantea is a species of plate coral or leaf coral belonging to the genus Pavona. The species was first described by Addison Emery Verrill in 1869. This coral is an important reef builder, meaning it creates a structure for the reef and a habitat forother marine species.

Pavona gigantea is common in shallow, protected waters. This species sees a natural growth rate of about 9 to 12 millimeters peryear. This coral can also develop large colonies of plates that cangrow from 8 to 10 meters in diameter. They have visible corallites that are 3 to 6 millimeters wide.

This species has clearly defined corallites with thick walls and radial elements. It has well-developed columellae. The tentacles ofthe colonies extend during the day, giving them a furry appearance.

Pavona explanulata, is a similar species which has similar corallite structures, but does not form massive colonies.

Background
Pavona gigantea grows in plate formation, which makes fragmenting and harvesting for scientific research relatively easy. Often, younger growth along a plate's edge is thin and easier to harvest. As the coral gets older it forms thicker and denser plates. Calcification of Pavona gigantea is frequent and could hint at the coral’s potential ability to survive in a wide range of environmental conditions.

Distribution
Pavona gigantea grows along the coast of Mexico, Ecuador, and the Galapagos Islands in the Pacific Ocean. The species is found in the Mid-Western Pacific (the body of water between Japan and New Guinea) on reefs in the middle of the ocean. They live in areas with seasonal upwelling. These corals are benthic and sessile.

Diet
Pavona gigantea eats and absorbs organic matter in the form of particulate matter anddissolved matter to get food and nutrients. Their consumption of plankton is limited tozooplankton between 200-400 μm. While at times they use their tentacles to obtain food, Pavona gigantea, like other hard corals, receives most of its energy from its symbiotic relationship with Zooxanthellae. They harness energy through photosynthesis. In this relationship, the Zooxanthellae give energy and nutrients, and the coral offer shelter and protection.

Reproduction
Pavona gigantea colonies are typically gonochoristic, broadcast spawners. They reproduce better in upwelling and subtropical areas, as these are areas that are nutrient-rich. Reproduction is influenced by surface temperature and daylight hours. Both male and female colonies release eggs into the water column, where they then mix during a spawning event. Normal spawningoccurs between May and July, at the start of the rainy season. Pavona gigantea has also been found to have hermaphroditic colonies in some studies. This is likely an instance of sequential cosexuality, which is when corals begin their reproductive life as males and then become hermaphroditic late on. There has been a suggestion that sequential cosexuality is an adaptation to increase connectivity among populations and ensure sexual reproduction.

Life Cycle
After a spawning event where a coral egg and sperm join together, the zygote develops. The zygote then transforms into a planktonic planula larva. Metamorphosis begins with the early formation of tentacles, septa, and pharynx before larval settlement at the aboral end. This coral reaches maturity at 19 years old.